I would love it if more companies would get involved with FOSS communities, either by sponsoring work, or getting involved directly, but I would still argue that it's against the spirit of FOSS (and the letter of most licenses) to try and force them to.
When we choose to put our software out in the world under permissive licenses, we can't really turn around and complain when people make use of it in ways that are beneficial to them. On that basis, I object to the use of the word "exploit" in its negative sense.
Edit: I'd like to add one thought - there are different groups of people who could benefit by greater engagement from large corporate use of FOSS. Two that come to mind easily are the funded startups trying to find viable FOSS business models; I admire their optimism and their goals, and wish them luck. The second is individuals and small groups who tirelessly maintain incredibly important things that the rest of us take for granted and have to fight tooth and nail for every grant, every hour of their own spare time and every hour of their employer's time, to keep those things going for us. If I have to choose a group to care about supporting, it's definitely going to be the latter, for whom I have immense respect, undying gratitude, and sadly insignificant donations.